Answer

Verified

414k+ views

**Hint:**Whenever there is a product of the two functions, then integration by parts or partial integration should be used. For instance, if and are the function of x, the integration of \[\int {u.vdx} = u\int {vdx} - \int {\left[ {\left( {\dfrac{{du}}{{dx}}} \right)\int {vdx} } \right]} dx\] , where $u = $ first function and $v = $ second function.

**Complete step by step solution:**$\int {x\sin x = - x cosx + \alpha } ......(1)$

From the integration it is clear that it is a product of two functions of x. Therefore, integration by parts should be used to evaluate the integral.

Let us assume x as the first function and as the second function.

\[I = x\int {\sin xdx} - \int {\left[ {\left( {\dfrac{{d\left( x \right)}}{{dx}}} \right)\int {\sin xdx} } \right]dx} ......(2)\]

The integration of $\int {\sin xdx = - co} sx$ and the differentiation of $x = 1$ , put the value in equation (2)

$I = - x\cos x + \int {\cos xdx} ......(3)$

The integration of \[\int {\cos xdx = \sin } x\] put the value in equation (3)

$I = - x\cos x + \sin x + C......(4)$

Where, C is a constant and known as constant of integration.

Comparing equation (4) and (1), it is clear that

The value of $\alpha = \sin x + C$

Hence, the correct option is (A).

**Note:**The choice of the first and second function should be in accordance with the thumb rule, which says that choose the function in the order of ILATE where I is the inverse trigonometric function, L is the logarithmic function, A is the algebraic function, T is the Trigonometric function and E is the exponential function.

For instance in $\int {x\cos x} $ x is the first function and is the second function because x is the algebraic function and cosine function is the trigonometric function. So the preference for first function is given to x.

Recently Updated Pages

What number is 20 of 400 class 8 maths CBSE

Which one of the following numbers is completely divisible class 8 maths CBSE

What number is 78 of 50 A 32 B 35 C 36 D 39 E 41 class 8 maths CBSE

How many integers are there between 10 and 2 and how class 8 maths CBSE

The 3 is what percent of 12 class 8 maths CBSE

Find the circumference of the circle having radius class 8 maths CBSE

Trending doubts

Difference Between Plant Cell and Animal Cell

Give 10 examples for herbs , shrubs , climbers , creepers

The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths

Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE

Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

List some examples of Rabi and Kharif crops class 8 biology CBSE

Which are the Top 10 Largest Countries of the World?

The provincial president of the constituent assembly class 11 social science CBSE

Write the 6 fundamental rights of India and explain in detail